Forgery, deceive or injure another, he falsely makes, completes or alters a written instrument which is or purports to be. Criminal possession of a forged instrument in the third degree is a class A misdemeanor forgery crime and can result in up to one year in jail.A FORGED INSTRUMENT means a written instrument which has been falsely made, completed or altered. Falsely Alters in a Possession of a Forged Instrument Case. At what point did you cross the line? Criminal Possession of a Forged Instrument in the Third Degree is a Class A misdemeanor. Forgery is the making of or creation of a false document to make it appear as though it was the real deal with the intent to defraud.